Relay operating by electrocapillarity



Dec. 15, 1964 J- BOURDEL RELAY OPERATING BY ELECTROCAPILLARITY Filed June 27, 1962 INVENTOR J ICOUES Baa/ma.

ATTORNEYS United States Patent 3,161,750 RELAY OPERATING BY ELECTROCAPILLARITY Jacques Bourdei, 8 Rue Marat, St. Cyr lEcole (Seine-et-0ise), France Filed June 27, 1962, Ser. No. 205,643 Claims priority, application France, July 3, 1961, 866,814 Claims. (Cl. 200-152) The present invention relates to a new relay system by means of which it is possible to obtain very good contacts by employing extremely low control energy.

It is known that when a bead of mercury or of a similar conductor disposed in a capillary duct otherwise filled with an electrolyte is traversed by an electric current, the surface tensions at the interfaces are modified (electrocapillarity eifect) and that an extremely weak current is suflicient to displace the said head.

The relay according to the invention utilises the forces generated by the electrocapillarity effect in order to displace in an insulating liquid medium a bead of mercury which closes the contacts of the relay.

This relay is essentially characterised in that it comprises, in a completely closed duct, an electrolyte separated from an insulating liquid by two flexible partitions, two electrodes in the said electrolyte, an insulating partition situated between the two electrodes and formed with a large number of capillary passages each containing a bead of mercury movable by electrocapillarity in the direction of either of the flexible partitions, contacts situated within the insulating liquid in two enlarged portions of the said duct which are separated from one another by a constriction, and a bead of mercury which can be introduced at will into either of the two enlarged portions, under the action of the displacement of the electrolyte, whereby the switching of the relay is eifecte d.

In addition, the capillary passages are so shaped as to ensure a stable positioning therein of the beads of mercury.

Further features of the invention will become appparent from the following description of one form of construction of a relay operating by electrocapillarity, which is given by way of example only and which is illustrated insection in the single figure of the accompanying draw- 1ng.

In this figure, the relay comprises a continuous closed duct 1 of substantially semi-annular form, which is divided by two flexible partitions 4 and 4a into two parts 2 and 3, the part 2 constituting a reservior for the electrolyte and the part 3 constituting a reservoir for an insulating liquid.

The reservoir 2, which is situated in the cylindrical portion of larger cross-section, is filled with an electrolyte such as H 80 NaOH or any other similar electrolyte. It contains two electrodes 5 and 5a, for example of platinum, and equidistant from the latter, a partition 6 consisting of glass, plastic material or other material, which is formed with a large number of capillary passages 7 of very small diameter (for example =0.2 mm.), which for the sake of clarity have been shown on a large scale in the figure.

The capillary passages 7 are perpendicular to the flexible partitions 4- and 4a and are widened in their central portion so as to maintain therein, in a stable position, mercury heads 8 which are displaceable by electrocapillarity under the action of the current flowing through the electrodes.

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The reservoir 3 is filled with an insulating liquid, for example hexane. On either side of the reservoir 2, its cross-section decreases in the direction of its central portion, at which it comprises two substantially spherical bulges 9, 9a separated by a constriction 12, in which bulges the contacts 10, 10a of the relay are fixed. A bead of mercury 11 fills one of the chambers consisting of the said bulges, for Example 9, and thus closes the corresponding contacts 10.

In the inoperative position, the mercury beads 8 are situated in the widened capillary portions. When a voltage (of the order of 1 v.) is applied to the electrodes 5 and 5a, the electric current flowing through the electrolyte passes through the mercury beads, which move in the capillary passages in the direction of the positive or negative electrode, depending upon the nature of the electrolyte. In the case of the embodiment described, the direction of the current is such that the mercury beads are directed towards the partition 4. This movement repels the electrolyte and exerts a pressure on the said partition 4. The latter becomes deformed and transmits the pressure which it has received to the insulating liquid in contact with the mercury head 11 for closing the contacts.

On the other side of the partition 6, the displacement of the mercury heads 8 and consequently that of the electrolyte decreases the pressure on the wall 4a. The insulating liquid and consequently that portion of the mercury bead 11 which is adjacent the chamber 9a therefore undergo a pressure reduction.

Under the action of the pressure difierences acting thereon, the mercury bead 11 is forced into the chamber 9a, thus opening the contacts 10 and closing the contacts 10a.

An impulse in the opposite direction would again dis-,

place the mercury beads 8, but this time towards the partition 4a, so as to drive the mercury bead 11 towards the chamber a and thus to close the contacts 10a.

The device by which the electrodes 5 and 5a is fed has not been shown. This device consists of any known means suitable for supplying impulses in alternate directions so as to displace the mercury beads 8 successively towards the partition 4 and then towards the partition 4a.

Deformable systems or means 13 or any conventional type for absorbing any thermal expansions are mounted in the wall of the reservoir 2 on either side of the partitions 6.

Since the impulse necessary for the movement of the mercury beads 8 is extremely small, the bistable relay thus provided is very sensitive and requires only very low control energy, the order of magnitude of the energy re-' quired to move the mercury head from one contact to the other being only 10- to 10- joule.

I claim:

1. A relay operating by electrocapillarity, characterised in that it comprises, in a completely closed duct, an electrolyte separated from an insulating liquid by two flexible partitions, two electrodes in the said electrolyte, an insulating partition disposed between the two electrodes and formed with a large number of capillary passages each containing a bead of mercury movable by electrocapillarity in the direction of either of the flexible partitions, contacts situated within the insulating liquid in two en larged portions of the said duct which are separated from he another by a constriction, and a bead of mercury in aid duct and displaceable at Will into either one or the ther of the two enlarged portions under the action of 1e displacement of the electrolyte, whereby the switch- 1g of the relay is effected.

2. A relay according to claim 1, wherein the capillary assages include widened central portions for maintaining he mercury beads in a stable position.

3. A relay according to claim 1, wherein the portion f said duct containing said electrolyte includes deformable means for absorbing thermal expansion of said electrolyte.

4. A relay according to claim 1, in which said electrodes are positioned equidistant from said partition.

5. A relay according to claim 1 in which said duct is continuous.

No references cited.

BERNARD A. GILHEANY, Primary Examiner.

10 ROBERT K. SCI-IAEFER, Examiner. 

1. A RELAY OPERATING BY ELECTROCAPILLARITY, CHARACTERISED IN THAT IT COMPRISES, IN A COMPLETELY CLOSED DUCT, AN ELECTROLYTE SEPARATED FROM AN INSULATING LIQUID BY TWO FLEXIBLE PARTITIONS, TWO ELECTRODES IN THE SAID ELECTROLYTE, AN INSULATING PARTITION DISPOSED BETWEEN THE TWO ELECTRODES AND FORMED WITH A LARGE NUMBER OF CAPILLARY PASSAGES EACH CONTAINING A BEAD OF MERCURY MOVABLE BY ELECTROCAPILLARITY IN THE DIRECTION OF EITHER OF THE FLEXIBLE PARTITIONS, CONTACTS SITUATED WITHIN THE INSULATING LIQUID IN TWO EN- 